FMIL: Remove function `fmiGetPartialDerivatives`, which was removed from the FMI2 spec, for #3241
FMIL: Merge and rename some functions for #3241.
 * `fmiTerminate`: make common between me and cs
 * `fmiTerminateSlave`: remove / use `fmiTerminate` instead
 * `fmiResetSlave`: rename to `fmiReset`, make common
FMIL: Add functions `fmiSetupExperiment`, `fmiEnterInitializationMode`, and `fmiExitInitializationMode` for #3241
FMIL: Add functions `fmiEnterEventMode`, `fmiNewDiscreteStates`, and `fmiEnterContinuousTimeMode` for #3241
FMIL: Add loading of functions `fmiSetupExperiment`, `fmiEnterInitializationMode`, and `fmiExitInitializationMode`, and implementations in test FMUs, for #3241. Also fix some related naming convention mistakes
FMIL: Make `fmiSetupExperiment`, `fmiEnterInitializationMode`, and `fmiExitInitializationMode` in FMI2 test FMUs do together what `fmiInitializeModel` / `fmiInitializeSlave` were doing; call the former instead in import tests, for #3241
FMIL: Remove functions `fmiInitializeModel` and `fmiInitializeSlave` from FMI2 code, for #3241